The mass murders that occured in Katyn forrest, in Poland, was for years blamed on Germany.
The Katyn massacre was a mass murder of 22 000 of Polish prisoners of war (primarily military officers), intellectuals, policemen, and other public servants by the Soviet NKVD, based on a proposal from Lavrentiy Beria to execute all members of the Polish Officer Corps. Dated March 5, 1940, this official document was then approved (signed) by the entire Soviet Politburo including Joseph Stalin and Beria.
Russia carried out the massacre, and America knew the truth, that the Russians were responsible, and this was yet another lie about National Socialist Germany that they told to the world.

From 28 December 1945 to 4 January 1946, seven Wehrmacht servicemen were tried by a Soviet military court in Leningrad. One of them, Arno Düre, who was charged with murdering numerous civilians using machine-guns in Soviet villages, confessed to having taken part in burial (though not the execution) of 15,000 to 20,000 Polish POWs in Katyn.

For this he was spared execution and was given 15 years of hard labor. His confession was full of absurdities, and thus he was not used as a Soviet prosecution witness during the Nuremberg trials. He later recanted his confession, claiming that he was forced to confess by the investigators. At the Nurembourg trials, similar absurd confessions were forced in such a way, many, were later retracted.

In 1990, Mikhail Gorbachev and a number of authorities admitted that Stalin and the Soviet leadership were responsible for ordering the Katyn massacre, after 50 years of Soviet lies, suppression, exile, and execution of the relatives of the victims and of those who brought the truth forward.

During World War II, both Churchill and Roosavelt and their administrations hid the truth about Katyn

Newly declassified U.S. army documents reveal that two American POWs sent secret coded messages to Army intelligence after their 1943 visit to Katyn, pointing to Soviet guilt for the 1940 massacre.
After witnessing rows of corpses in the Katyn forest, on the western edge of Russia, the American POWs told Washington they believed the German claims that Soviets had carried out the killings of 22,000 Polish officers.
Having seen the advanced state of decay of the bodies, the POWs concluded that the killings must have been carried out by the Soviets rather than the Germans who had only recently invaded the area surrounding the Katyn forest.

So after 50 years, this lie about the “Nazi’s” was exposed. Many other lies have also been exposed, and more and more people are learning of them. Our governments knowingly lied about this brutal massacre, how many other massive lies have they told?
And who is still stupid enough to trust them?